In an opinion (download pdf) filed today by Judge Thomas of the United States Ninth Circuit of Appeals, Judge Thomas says:

The question of direct copyright infringement is not at issue in this case. Rather, the Copyright Owners contend that the Software Distributors are liable for the copyright infringement of the software users. The Copyright Owners rely on the two recognized theories of secondary copyright liability: contributory copyright infringement and vicarious copyright infringement. Ellison v. Robertson, 357 F.3d 1072, 1076 (9th Cir. 2004). We agree with the district court